1. Field of the Invention
The present invention relates to a network access control method and apparatus in a code-division multiple access (CDMA) system where a plurality of wireless terminals are allowed to simultaneously access the CDMA mobile communications network.
2. Description of Related Art
In principle, CDMA is not a time-based access system such as time-division multiple access (TDMA). Accordingly, the CDMA system permits a plurality of CDMA terminals to simultaneously send different network access requests to the network on the common channel. Even if different network access requests has been simultaneously received, they can reach the network with high probability or less probability of collision in radio section.
In the CDMA system, however, it is conceivable that instantaneous processing congestions are likely to occur in the network side, compared to the TDMA system. More specifically, radio-system/wired-system hardware settings are needed for each network access request. Accordingly, when a plurality of simultaneous access requests occur within a time period required for the radio-system and wired-system hardware settings, notification of access permission/rejection for a network access request is delayed, resulting in time-out in an originating CDMA terminal. When the time-out occurs, the originating CDMA terminal resends the same network access request to the network. Accordingly, such retransmission of the network access request accelerates the processing congestions in the network side and at worst a system failure may occur.
As described above, when CDMA terminals start network accesses in a CDMA system, the possibility of heavy instantaneous loads on the network may be higher than in the case of a TDMA system. Therefore, it is necessary for the network to increase in processing capacity and efficiently and properly control such access requests of user terminals even when the network is instantaneously overloaded by user terminals starting network accesses.